With the prevalence of build tools like Gulp, Grunt, Babel, and Webpack, which all use Node, I feel there is a need to have a basic understanding of how Node streams data, how to pipe it through different functions, and how to use / create modules as well as when to use a module / package.
I'm not saying you need to know how to build a app and master the event loop but I feel a front-end developer should be able to implement their own build systems.
I hope this is the elaboration you were looking for @josfaber.